Transfer record sheet for making multiple copies of a single heat impression

ABSTRACT

THIS INVENTION RELATES TO A SELF-REVELATION HEAT-ACTIVATABLE SHEET-LIKE TRANSFER PRINTING MEMBER COMPRISING A TRANSLUCENT SUPPORT SHEET AND A BACK-COATING OF HEATTACKIFIABLE TRANSFER INK THAT NORMALLY IS SOLID AND NORMALLY REVEALS A LIGHT-REFLECTING SURFACE AT THE INTERFACE OF THE SUPPORT SHEET AND THE COATING, AS VIEWED FROM THE FRONT UNCOATED SIDE, AND THE COATING, AS VIEWED FROM THE FRONT UNCOATED SIDE, BUT IS IRREVERSIBLY DARKENED WHEN AND WHERE HEATED TO THE TACKIFIABLE CONDITION. THE HEATTACKIFIED COATING IS AN INK-SOURCE FOR MAKING A TRANSFER CEIVING SHEETS BROUGHT INTO PRESSURE CONTACT THEREWITH IN SUCCESSION. AN IMAGE MADE BY A HOT IMAGE-FORMER APPLIED TO THE SHEET, PREFERABLY TO THE UNCOATED SIDE, LEAVES A CORRESPONDING DARK IMAGE AGAINST THE LIGHT SURFACE AT THE INTERFACE, TO BE SEEN THROUGH THE SUPPORT SHEET.   D R A W I N G

TRANSPARENT SH EET O F Feb. 9, H, M TRANSFER RECORD SHEET FOR MAKING MULTIPLE COPIES OF A SINGLE HEAT IMPRESSION Filed Aug. 28. 1968 TRANSFER COATING OF HEAT MELTABLE MIXTURE 0F RESIN AND PLASTICIZER, HAVING A RETARDED REHARDENING CHARACTERISTIC AND COLORLESS PARTICLES OF CO-REACTANT COLOR- FORMING MATERIAL SOLUBLE IN THE MELT, TO GIVE THE MIXTURE A WHITE REFLECTANCE IN INCIDENT WHITE LIGHT AND COLORING WHERE MELTED TRANSPARENT SHEET OF SUPPORT MATERIAL TRANSFER COATING OF HEAT MELTABLE MIXTURE OF RESIN AND PLASTICIZER, HAVING A RETARDED RE-HARDENING CHARACTERISTIC AND HAVING BLACK OR DARK PIGMENT AND DARK DYE DISTRIBUTED IN IT SUB-COATING OF WHITE OR LIGHT COLORED PARTICLES OF PIGMENT INVENTOR HENRY H. BAUM HIS ATTORNEY United States Patent Oflice 3 561,991 TRANSFER RECOR D SHEET FOR MAKING MULTIPLE COPIES OF A SINGLE HEAT IMPRESSION Henry H. Baum, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Aug. 28, 1968, Ser. No. 756,008 int. (11. B41m 5/10 US. Cl. 117-361 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a self-revelation heat-activatable sheet-like transfer printing member comprising a translucent support sheet and a back-coating of heattackifiable transfer ink that normally is solid and normally reveals a light-reflecting surface at the interface of the support sheet and the coating, as viewed from the front uncoated side, but is irreversibly darkened when and where heated to the tackifiable condition. The heattackified coating is an ink-source for making a transfer print against each of a number of light-colored copy-receiving sheets brought into pressure contact therewith in succession. An image made by a hot image-former applied to the sheet, preferably to the uncoated side, leaves a corresponding dark image against the light surface at the interface, to be seen through the support sheet.

Tackified image areas of this novel sheet stay tacky long after the activating heat has been withdrawn and for some minutes stay tacky while cooled to room tem perature. As long as the ink lasts, a tacky area may be used as a pattern ink-source to make successive copies on copy-receiving sheets brought into contact therewith. The persistent tacky state of an area permits a number of images to be made in timed succession, side by side. When finally solidified, an image area forms a permanent copy of what has been printed and copied by its contrast with the light background of the untackified areas.

The dark image in one form (Type I) of the invention is made by generation of color and in another form (Type II) of the invention is made by solution and liquid migration of inherently color material. Each of the two forms of the invention results in the making of a permanent right-reading image in the sheet-like transfer member itself, and this is the principal novelty of utility and construction provided by the invention.

This is an improvement over prior record material shown in Dulmage et al. United States Pat. No. 3,260,612, which issued July 12, 1966, and which discloses no means for revealing the pattern of the hot transferable ink image as viewed from the uncoated side of a transparent or translucent support sheet; and also is an improvement in that respect over applicants disclosure in application for United States Letters Patent Ser. No. 619,609, filed Mar. 1, 1967. Even if the base sheets of the disclosures of the cited patent and application were transparent, they disclose no provision for displaying a right-reading image against a light background.

THE PRIOR ART It is acknowledged that paper coatings that combine the characteristics of becoming soft when heated and remaining soft for a period after returning to room temperature have been known since the issue of United States Pat. No. 2,462,029 to Lloyd M. Perry on Feb. 15, 1949, where an adhesive coating was provided. On July 12, 1966, William J. Dulmage, Sterling S. Sweet, and William A. Light had United States Pat. No. 3,260,612 issue on their application, applying the principle to transfer record material 3,561,991 Patented Feb. 9, 1971 to make successive copies of a heat-formed image. On Mar. 1, 1967, this applicant filed said application for United States Letters Patent Ser. No. 619,609 for an improved and superior transfer coating material that, once heat-softened, remains fused for a while and yields successive copies of heat-formed dark-colored images by repeated contact with copy paper sheet material.

None of the foregoing disclosures in any way show any means for making the heated image ink-source visible from the uncoated side of the transfer sheet as a dark area against a light background.

THE INVENTION Primarily this invention provides a transparent base sheet having a complex coating on one side that ordinarily shows white or light color at the interface of the coating and the base sheet and a dark color at the interface wherever heated to a critical temperature as by a hot printing member. This color may be produced by chemical reaction in situ at the interface by the applied heat, or may be material that migrates to the interface because of the heat, according to the construction of the coating. In the construction where the color is generated in situ (Type I), small colorless particles of co-reactant color-forming material are dispersed throughout a heat-meltable coating with the retarded solidifying property, said co-reactant particles being brought together in reaction-contact solution when heated to the critical melting temperature. This color appears at the interface, extends directly to the outer surface of the coating, and is transferable to copy paper brought into contact therewith. The transfer material is substantially used up after a number of copies are made in succession. Even though the image temperature drops to room temperature (20 to 25 degrees centigrade), the melted state of the ink-source image persists. Put in other words, hardening of this image area is retarded, even though cooled to room temperature, for a time measured in tens of minutes. In the construction where colored material is used (Type II), the meltable heat-colorable transfer material is coated over a white liquid-penetrable sub-coating. When melted to a liquid, the melted tackified transfer coating dissolves dye particles dispersed therein, migrates through the white coating to appear at the inter face, and also is available at the outside surface for contact transfer to a copy sheet by reason of the tackiness.

The invention will be described with reference to the drawing, which shows, in FIG. 1, a diagrammatic sketch of a heat-sensitive transparent base web transfer sheet of Type I, in which the transfer coating has dispersed in it particles of colorless chromogenic material and colorless particles of co-reactant to generate color, where melted, and

FIG. 2 is a diagrammatic sketch of a transparent base Web sheet of Type II with a transfer coating of particles of dye soluble in the melted transfer coating material.

In both types of meltable coating, the chief non-color components are a resin and a plasticizer which, once melted together at a critical temperature above normal room temperature, form a mixture which has a congealing temperature lower than the critical temperature and a delayed or retarded hardening characteristic.

The eligible support sheet material may be either translucent paper or a film of polymeric material thin enough to yield to marking pressures necessary to transfer the coating material and resistant to attack by the coating slurry liquid. Ordinary carbonizing tissue paper is translucent enough to show a mark of blackish hue against a light background. Commercial onion-skin paper likewise works well. A five-pound sheet per ream of 500 sheets equaling 3,300 square feet is about minimum weight for tissue paper for transfer coatings. If polymeric film sup port sheet material is used, one with greater transparency than thin paper will yield prints more easily seen. Other than for these qualities, the nature of the base sheet is unimportant if it readily conducts heat of an applied hot printing member. Among polymeric material may be mentioned, as eligible, films of cellulose acetate, cellulose acetate butyrate, cellophane, polyester, polyethylene, polyethylene terephthalate (Mylar), and equivalents. All such base sheets may be tinted lightly with transparent colors if desired.

In both types of the invention, the materials are so chosen that the re-hardening is retarded long enough to allow repeated transfer images to be made on plain copy sheets brought into contact with the melted image surface, the coating being used up incrementally until exhausted or else re-hardened by passage of time and heat loss, which may occur in ten to twenty minutes at room temperature.

One of the restrictive features of the invention is that the liquid used in the composition of materials used for coating the transparent support sheet should not dissolve the color-reactant materials or the colored materials lest a premature all-over coloring occur by reaction or liquid transportation of the coloring materials to make reaction contact, or by solution. The color reactants of Type I and the dyes of Type II should dissolve in the melt but not in the vehicle used in the coating slurry. Therefore the liquid coating vehicle of choice is made with the purpose in mind of avoiding premature coloring, and the coating composition is unique in that respect over anything shown in the prior art and therefore is itself claimed as an aspect of the invention.

COATINGS Example 1 This is a Type I coating and constitutes the preferred form of the invention. It is to be coated as a liquid slurry on 5 to pounds per ream weight of 3,300 square feet of translucent onion skin paper of smooth finish. The liquid of the slurry is not a solvent for the particulate co-reactant color-formers, which are bis-phenol A and crystal violet lactone, which latter is 3,3 bis (p-dimethylaminophenyl)-6-dimethyl amino phthalide and which is normally white but turns dark blue on reaction contact with a suitable acidic substance. The coating composition itself employs a dryable liquid vehicle of isoparaffinic constituents of inert properties and high evaporation rates. The vehicle may be purchased under the trade name Isopar, sold by Humble Oil and Refining Company, of Houston, Tex., United States of America. Their Grade E has been found suitable as the vehicle for the dispersion of the color-forming materials bis-phenol A as the acid and crystal violet lactone as the base chromogenic reactant. They do not form reaction contact in the Isopar E, the vehicle evaporating without odor sufficiently rapidly to permit the coating to be applied to the base sheet and dried on conventional paper-coating apparatus. Of course, any fast-drying inert liquid vehicle may be substituted therefor, as it acts only as a liquid vehicle. Crystal violet lactone may be made according to directions given in United States Pat. Re. 23,024, issued Aug. 17, 1948, on the application of Clyde S. Adams, the parent United States Pat. No. 2,417,897, issued Mar. 25, 1947, originally disclosing this normally colorless or white dye precursor, which turns to its deep blue colored form in various contact environments with acids, as in adsorption contact with attapulgite clay or on contact with a solution of acidic phenolic materials of oil-soluble properties. The acidic material chosen for this preferred embodiment is bis-phenol A of the structure which can be otherwise stated as 4,4'-isopropilidene diphenol, or as 2,2-bis(p-hydroxy phenyl) propane. Various oil-soluble phenolic polymeric materials may be used as equivalents either in whole or in part. Many of these polymeric materials are disclosed in application for United States Letters Patent Ser. No. 392,404, filed by Robert E. Miller and Paul S. Phillips, Jr., on Aug. 27, 1964. A corresponding issued patent, Br. 1,053,935, was granted in England on July 22, 19655. In the disclosure of Miller and Phillips is mentioned a large number of the oil-soluble phenolic polymeric materials of acid reaction potential; particularly, phenol-aldehyde, phenol-acetylene, and maleic acid-rosin resins; hydrolyzed styrene-maleic anhydride co-polymers; and many other groups. Specific polymers are identified in said disclosures, and restort may be had to them for a choice of acid polymeric materials of oil-soluble nature. The color-forming chromogenic colorless dye precursors may be chosen from many colorless diaryl phthalides, leucauramines, acyl auramines, unsaturated aryl ketones, basic mono azo dyes, colorless Rhodamine 5 lactams, polyaryl carbinols, and 8 methoxy benzoindolinospiropyrans mentioned in said last-named application and patent. The choice of colorants is not critical and does not form an important part of the invention, which is to provide a combination of such reactant material particles interspersed in a composition which when dried on a substrate of transparent or translucent propertties will, upon being impressed by a hot printing member, yield a tacky reusable colored ink-source pattern which is visible from the uncoated side of the support sheet.

The preferred composition is made of three dispersions, A, B, and C, and a solution D.

Dispersion A Eighteen grams of finely-divided crystal violet lactone is dispersed in a solution of 2 grams of Piccotex resin in 30 grams of Isopar E. Isopar E is an isoparafiinic hydrocarbon fraction of boiling point range of 240 to 290 degrees Fahrenheit and 99% isoparafiinic content, sold by Humble Oil and Refining Company, of Houston, Tex., United States of America. Piccotex is a styrene homolog copolymer resin, obtainable from Pennsylvania Industrial Chemical Corporation, of Clairton, Pa, United States of America, which in Grade 100 has a normal softening point of 100 degrees Centigrade and which is modified by the plasticizer in Dispersion C upon melting therewith.

Dispersion B Eighteen grams of finely-divided bis-phenol A is dispersed in a solution of 2 grams of the specified Piccotex dissolved in 30 grams of the specified Isopar E.

Dispersion C Eighteen grams of finely-divided Santicizer 3, which is a plasticizer of the structure and of the formula N-ethyl-para-toluene sulfonamide, obtainable from Monsanto Chemical Company, St. Louis, Mo., United States of America, is dispersed in 30 grams of Isopar E. Suitable plasticizer equivalents may be used to adjust the softening point of the dried coating, of which it forms a part when dried, to yield a transferable tacky condition thereof on application of printing temperature.

Solution D 7.5 grams of Vistanex, an adhesive polyisobutylene, available from Enjay Chemical Company, a Division of Humble Oil and Refining Company, of 60 W. 4th St., New York, N.Y., United States of America, is dissolved in 92.5 grams of Isopar E. This serves, when dried, as

a binder for the dried coating ingredients.

The coating mixture is:

1.5 parts by weight of Dispersion A 7.1 parts by weight of Dispersion B part by weight of Dispersion C 7.5 parts by weight of Solution D.

This is coated on the selected base stock support sheet at a rate that will yield a dry Weight coating of 10 pounds per specified ream of 3,300 square feet, more or less. The dried 10-pound coating composition is Percentage Crystal violet lactone 5.4 Bis-phenol A 25.6 Santicizer #3 54.0 Piccotex 100 9.4 Vistanex 5.6

This coated sheet, subject to an applied printing member having a temperature of 200 to 300 degrees Fahrenheit for a fraction of a second, melts the dried coating, causing it to assume a dark-blue-colored state throughout the coating layer in the heat image area, and this area is apparent, or self-revealing, as viewed through the translucent or transparent support sheet and remains soft and tacky for ten to twenty minutes, during which time copies of the printed data may be taken from the soft area by copy sheets pressed directly thereagainst.

Because the yield of color may not be fully developed by the fluid contact between the co-reactants in the tacky warm areas, it may be wise in some instances to sensitize the copy-receiving sheet with an acid substance, such as bis-phenol A or attapul ite, to develop any unreacted chromogenic material that has not assumed the colored state.

Example 2 This Example 2 is a Type I coating in which a Dispersion E is provided to be used with Dispersions B and C and Solution D of Example 1 to form a coating slurry.

Dispersion E Eighteen gams of 6'-chloro, 8-methoxy derivative of 1,3,3-trimethylindolinebenzopyrylospiropyran having the structure is dissolved in grams of Isopar E.

The slurry is composed of 3.8 parts by weight of Dispersion E, 5.8 parts by weight of Dispersion B, 15 parts by weight of Dispersion C, and 7.5 parts by weight of Solution D. This is coated on suitable transparent or translucent substrate sheet material at a rate to yield a dry coating of 10 pounds per specified ream of 3,300 square feet, having the composition Percent by weight Benzospiran compound 10.1 Bis-phenol A 20.9 Santicizer 3 54.0 Piccotex 100 9.4 Vistanex 5.6

This coating also is normally white but turns dark blue and softens to transfer consistency with the property of retarded hardening upon being heated for a fraction of a second to from 200 to 300 degrees Fahrenheit. This example merely substitutes a requisite amount of the benzospiran compound of basic properties and normally colorless state for the crystal violet lactone of Example 1.

Various substitutions and blends of normally colorless chromogenic compounds taken from the stated eligible materials may be made in substantially the same amounts The benzospiran compound colors to a dark blue.

Example 3 For this example, a coating slurry is made according to Example 1, with an amount of Rhodamine [3 Lactam in place of the crystal violet lactone of Example 1 on an equal weight-for-weight basis. This yields red marks instead of the dark blue marks of Examples 1 and 2.

Example 4 This example is a Type II coating on the transparent or translucent sheet material wherein the light color of the interface is caused not by dispersed particles of coreactant colorless materials in a meltable binder, but by dispersed particles of white-light-refiectant inert material dispersed in a suitable binder material which is coated as a sub-coating. An Overcoating is applied to the sub-coating that is pigmented or colored otherwise and softenable to a tacky, transferable condition to the degree of fluidity that permits the pigment or coloring material to dissolve in it and to strike through the sub-coating and appear as a colored area against a light background as viewed from the uncoated side.

(A) Sub-coating composition-22.5 grams of finely divided TiO is dispersed in a solution of 15 grams of half-second cellulose acetate-butyrate and 12.5 grams of Santicizer 3 dissolved in 80 grams of toluene and 20 grams of denatured ethyl alcohol.

(B) Overcoating composition-64 grams of Santi cizer 3, 5 grams of Methylene Blue SP color index Basic Blue 9, which may be purchased from National Aniline Division of Allied Chemical Company, 40 Rector St., New York, N.Y., United States of America, 5 grams of Nigrosine Base 2R color index solvent black 7 (Nigrosine spirit soluble), and 1 gram of Armid HT (which is a mixture of 22% hexadecanamide, octadecanamide, and 3% 9-octadecenamide and which acts, when melted, as a dye solution) are dispersed in a solution of 10 grams of the specified Vistanex" and 15 grams of the specified Piccotex resin in 200 grams of the specified Isopar E.

COMPOSITION OF DRIED COATING Undercoat A: Percent by weight TiO 45 Santicizer B 25 Cellulose acetate-butyrate 30 This is applied as a toluene slurry of 30% solids.

Overcoat B: Percent by weight Santicizer #3 64 Methylene Blue SP 5 Nigrosine Base 2R 5 Armid HT 1 Vistanex 10 Piccotex 15 This is applied in Iso-par E as a 30% solids slurry.

Undercoat A is applied first, allowed to dry, and then overcoated with Composition B, which, when dried, leaves ten pounds per specified ream dry weight.

The second coating slurry will not penetrate the first coating.

A heated printing instrument applied for a fraction of a second to bring the heated area to between 200 and 300 degrees Fahrenheit will, because of the melting and solubilizing of the materials, make corresponding black marks seen through the base sheet and yield a transferable source of black fluid ink to make repeated copies to the number of six or eight on plain paper if used within ten minutes or so.

Allowance for ambient temperature and heat-sink properties of the hot impression means must be taken into account in compounding the various compositions, which may be varied slightly to meet the conditions of use and the differences made necessary by the use of substantially equivalent materials as to function.

The use in and of itself of a transparent support web for transfer coating, even for one used with a hot printing member, is not considered patentable. The novelty of this disclosed transfer sheet is in providing a light background at the interface between a support sheet and a coating thereon, against which a hot melt data-representing area of the coating may be seen as a dark or dark-colored readable mark and still be useful in making multiple copies following an initial application of a hot printing member.

Where the Type II system, involving two coatings, is used, it is important that the vehicle of the overcoating slurry will not penetrate the undercoating.

The choice of plasticizer determines the melting point range of the coating and is so made that the coating begins to soften at about 110 degrees Fahrenheit, although this may be adjusted upwardly or downwardly to suit the conditions of use. Thus the application of a hot printing member to bring the coating a temperature of 200 to 300 degrees Fahrenheit is quite adequate for the specified materials, and this is under the disintegration temperature of most eligible sheet support materials.

What is claimed is:

1. A heat-image-revealing heat-activated transfer sheet for use with a hot imaging printing member for making a printed transfer image on each of a succession of copy sheets brought into contact therewith, the sheet consisting of a substantially visible-light-transparent support sheet web-material adapted to application on one sheet surface of a hot heat-imaging printing member and coated on the other sheet surface with a solid potential ink source coating that is, at normal room temperature, substantially colorless, light reflecting and solid, that is meltable to a tacky transfer condition when a printing member of substantially higher than room temperature is applied to the uncoated side of the support web material, the melted coating staying so melted for a period measured in tens of minutes after the printing member is withdrawn and the normal room temperature of the coating has been resumed by cooling, the coating being characterized by containing potential coloring material that develops color on the coatings becoming melted and in that capacity acting as a solvent for the potential coloring material, said potential coloring material being insoluble in said coating as applied, which color, when developed, can be seen as an image of the printing member as viewed through the transparent web from the uncoated side of the support web when the printing member is removed, whereby the colored image, when made, can be seen in the coating material before and after the coating has resolidified.

2. The sheet of claim 1 in which the colorless quality of the coating is attained by dispersing, in the coating, fine, light reflecting solid particles of co-reactant colorforming materials which become dissolved in the melted coating and make a distinctive color by co-reaction.

3. The sheet of claim 2 in which the color-reactant particles are particles of crystal violet lactone and particles of 4,4-isopropilidene diphenol dispersed in a resin-plasticizer mixture, said particles giving the coating a normal white light reflectance and which coating turns to a dark blue reflectance upon being heated to the melting point and remains the dark blue state after solidification.

4. The sheet of claim 1 in which the coating comprises a sub-coating consisting of a dispersion of a particulate white pigment in plasticized half-second cellulose acetate butyrate; and an overcoating of fine solid particles of intense soluble dye dispersed in a meltable dried coating of resin plasticized with the half-second cellulose acetate butyrate of the retarded solidification property, the dye particles solubilizing in the melt areas wherein the hot image is impressed to yield a dark color which will penetrate the sub-coating to reveal the image at the interface as seen through the support web and to provide a tacky transfer coating.

5. A heat-activated transfer sheet consisting of a substantially white solid coating supported on one surface of a translucent base sheet, the white coating comprising a colorless resin, a colorless heat-meltable plasticizer therefor, and small particles of color former, the color former particles being soluble in the resin-plasticizer melt formed when a hot printing member is applied to the uncoated surface of the base sheet, to form color, but being insoluble in said resin plasticizer material as applied, the plasticizer being selected to melt at the temperature induced in it by the hot printing member and to dissolve the resin, the colored printing-member-melted area being visible through the uncoated surface of the base sheet and the melted coating being a tacky colored ink reservoir available to make copies on each of a succession of copy sheets brought into contact with the melted image area material.

References Cited UNITED STATES PATENTS 2,686,676 8/1954 Rowe et a1. 11736.7 3,104,980 9/1963 Maierson 11736.4 3,156,183 10/1964 Bach 11736.7 3,242,122 3/1966 Cheng 1l736.8 3,261,023 7/1966 Light 11736.1 3,342,623 9/1967 Dulmage et a1 11736.1

FOREIGN PATENTS 1,373,659 8/1964 France 11736.1 531,369 10/1956 Canada 11736.7

MURRAY KATZ, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,561,991 February 9 15 Henry H. Baum It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4 line 7 "19655" should read 1965 Colun line 41, gams" should read grams lines 44 to 49 the formula should appear as shown below:

H C CH OCH Sighed and sealed this 29th day-of June 1971.

(SEAL) Attest: 

